nios2: Page table management

This patch adds support for page table management.

Signed-off-by: Ley Foon Tan <lftan@altera.com>

arch/nios2/include/asm/pgalloc.h

@@ -0,0 +1,86 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1994 - 2001, 2003 by Ralf Baechle
+ * Copyright (C) 1999, 2000, 2001 Silicon Graphics, Inc.
+ */
+
+#ifndef _ASM_NIOS2_PGALLOC_H
+#define _ASM_NIOS2_PGALLOC_H
+
+#include <linux/mm.h>
+
+static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
+	pte_t *pte)
+{
+	set_pmd(pmd, __pmd((unsigned long)pte));
+}
+
+static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
+	pgtable_t pte)
+{
+	set_pmd(pmd, __pmd((unsigned long)page_address(pte)));
+}
+#define pmd_pgtable(pmd) pmd_page(pmd)
+
+/*
+ * Initialize a new pmd table with invalid pointers.
+ */
+extern void pmd_init(unsigned long page, unsigned long pagetable);
+
+extern pgd_t *pgd_alloc(struct mm_struct *mm);
+
+static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+	free_pages((unsigned long)pgd, PGD_ORDER);
+}
+
+static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
+	unsigned long address)
+{
+	pte_t *pte;
+
+	pte = (pte_t *) __get_free_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO,
+					PTE_ORDER);
+
+	return pte;
+}
+
+static inline pgtable_t pte_alloc_one(struct mm_struct *mm,
+	unsigned long address)
+{
+	struct page *pte;
+
+	pte = alloc_pages(GFP_KERNEL | __GFP_REPEAT, PTE_ORDER);
+	if (pte) {
+		if (!pgtable_page_ctor(pte)) {
+			__free_page(pte);
+			return NULL;
+		}
+		clear_highpage(pte);
+	}
+	return pte;
+}
+
+static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
+{
+	free_pages((unsigned long)pte, PTE_ORDER);
+}
+
+static inline void pte_free(struct mm_struct *mm, struct page *pte)
+{
+	pgtable_page_dtor(pte);
+	__free_pages(pte, PTE_ORDER);
+}
+
+#define __pte_free_tlb(tlb, pte, addr)				\
+	do {							\
+		pgtable_page_dtor(pte);				\
+		tlb_remove_page((tlb), (pte));			\
+	} while (0)
+
+#define check_pgt_cache()	do { } while (0)
+
+#endif /* _ASM_NIOS2_PGALLOC_H */

arch/nios2/include/asm/pgtable-bits.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2009 Wind River Systems Inc
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#ifndef _ASM_NIOS2_PGTABLE_BITS_H
+#define _ASM_NIOS2_PGTABLE_BITS_H
+
+/*
+ * These are actual hardware defined protection bits in the tlbacc register
+ * which looks like this:
+ *
+ * 31 30 ... 26 25 24 23 22 21 20 19 18 ...  1  0
+ * ignored........  C  R  W  X  G PFN............
+ */
+#define _PAGE_GLOBAL	(1<<20)
+#define _PAGE_EXEC	(1<<21)
+#define _PAGE_WRITE	(1<<22)
+#define _PAGE_READ	(1<<23)
+#define _PAGE_CACHED	(1<<24)	/* C: data access cacheable */
+
+/*
+ * Software defined bits. They are ignored by the hardware and always read back
+ * as zero, but can be written as non-zero.
+ */
+#define _PAGE_PRESENT	(1<<25)	/* PTE contains a translation */
+#define _PAGE_ACCESSED	(1<<26)	/* page referenced */
+#define _PAGE_DIRTY	(1<<27)	/* dirty page */
+#define _PAGE_FILE	(1<<28)	/* PTE used for file mapping or swap */
+
+#endif /* _ASM_NIOS2_PGTABLE_BITS_H */